/**
 * Created with IntelliJ IDEA.
 * Description:牛牛的并联电路
 * User: zjc
 * Date: 2022-06-02
 * Time: 22:40
 */
import java.util.Scanner;
public class Main{
    public static void main(String[]args){
        Scanner in = new Scanner(System.in);
        String input = in.nextLine();
        String [] num= input.split(" ");
        double []tem=new double [num.length];
        for(int i=0;i<num.length;i++)
        {
            tem[i]=Integer.parseInt(num[i]);
        }
        System.out.println(1.00 /((1.00/tem[0])+(1.00/tem[1])));
    }
}
